As a primary interface between the organism and its environment, the respiratory system is the target for a wide range of toxicants, including reactive gases, agricultural chemicals, and airborne pathogens and particles. Since it also receives the entire output of the right heart, it is also the target for a variety of circulating toxic compounds that enter the organism via the skin or gastrointestinal tract; as a consequence, agricultural chemicals that have the lungs as a target but are not incorporated into dusts or sprays can still cause toxicity by ingestion of contaminated food and drinking water or absorption through the skin. The overall goals of this research Core are to: (1) promote interdisciplinary research that will elucidate the cellular, metabolic, and molecular mechanisms that define and modulate the response of the respiratory system to environmental toxicants, and (2) provide information relative to the harmful effects of photochemical air pollution and other inhaled toxicants that will be useful in understanding the relative susceptibility of humans to harm from exposure to agricultural contaminants whose toxicity results from other metabolic pathways. Currently the Core members are pursuing projects focused on a number of areas of general concern for public health, especially as they relate to cross-contamination of urban and agricultural sectors.